Valve seat insert with soft landing insert design with contoured radii

ABSTRACT

A valve seat insert includes a top convex arcuate blend for improving fluid flow, and a valve seating surface for slowing down valve recession. The valve seating surface includes a radially outer convex arcuate segment defining an outer radius of curvature forming a first wear crown for contacting the valve at an early wear state, a radially inner convex arcuate segment defining an inner radius of curvature forming a second wear crown for contacting the valve at a later wear state, and a linear segment extending between the radially outer convex arcuate segment and the radially inner convex arcuate segment.

TECHNICAL FIELD

The present disclosure relates generally to engine valves and associatedhardware, and more particularly to a valve seat insert for an intakevalve or an exhaust valve that are configured to provide a long life viaa soft landing while not compromising other engine performances.

BACKGROUND

Gas exchange valves are used in internal combustion engines to controlfluid connections between the cylinder and a supply of intake air orintake air and other gases such as recirculated exhaust gas, or betweenthe cylinder and an exhaust manifold for expelling combustion productsduring operation. Designs are known wherein a single intake valve and asingle exhaust valve are associated with each cylinder in an engine, aswell as designs where multiple gas exchange valves of each respectivetype are associated with each cylinder. A camshaft, typically rotated athalf engine speed, is coupled with valve lifters, bridges, rocker arms,and/or other equipment for controlling the opening and closing of gasexchange valves at appropriate engine timings.

Gas exchange valves are moved out of contact with and into contact withthe engine head or a valve seat insert within the engine head to affecttheir opening and closing actions. Gas exchange valves may be movedbetween their open and closed positions with significant mechanicalforces. The in-cylinder environment is associated with combustiontemperatures of several hundred degrees along with relatively highpressures. These and other factors contribute to gas exchange valveoperating conditions being quite harsh. It has been observed that gasexchange valves and valve seats or valve seat inserts can exhibit aphenomenon over time known as valve recession. Over the course of anengine's service life, or between service intervals, the contactsbetween a gas exchange valve and its valve seat can number in themillions or potentially even billions.

The harsh conditions and great number of impacts can cause material ofwhich the gas exchange valve and/or the valve seat is formed to wearaway and/or become deformed, so that the valve “recedes” toward or intothe engine head further than what is desired. Where valve seat recessionbecomes severe enough engine operation or performance can becompromised, sometimes requiring a so-called top end overhaulprematurely. Engineers have experimented with a variety of differenttechniques attempting to ameliorate the extent and effects of valve seatrecession and other valve wear patterns. A continuing challenge toattempt valve or valve seat redesign are the often-unpredictable effectsthat altered geometry has on gas flow or other operatingcharacteristics. Gas flow patterns and/or efficiency can affectin-cylinder pressure and temperature, composition of a fuel and airmixture, or other parameters potentially impacting emissions reductionstrategies, engine efficiency, heat dissipation or thermal fatigue, orstill other parameters.

In certain types of engines, a high power density is desired. In suchapplications, such as a high power density C280 (diesel engine), G3600(gas engine) or other marine engines manufactured by the Applicant ofthe present disclosure is considered by some to be an industry leadersfor long top end life and durability. However, continuous improvement inthis area is warranted.

U.S. Pat. No. 4,728,078A discloses a ceramic valve seat that has roundededges to mitigate stress concentrations. However, this reference failsto disclose how to improve the longevity of a valve seat while alsomaintaining the other desired engine performances including fluidmechanics and power.

SUMMARY OF THE INVENTION

An engine head assembly according to an embodiment of the presentdisclosure for an internal combustion engine may comprise an engine headhaving a fluid conduit formed therein, a valve, and a valve seat insertpositioned at least partially within the engine head. The valve seatinsert may include an at least partially annular body, defining alongitudinal axis, and a radial direction that is perpendicular to thelongitudinal axis, a first axial end surface disposed proximate to theengine head, and a second axial end surface. The valve seat insert mayalso have a radially inner surface forming a throat, a radially outerperipheral surface defining a cooling gallery, and a valve seatingsurface disposed axially and radially between the radially inner surfaceand the second axial end surface. A top convex arcuate blend may extendfrom the first axial end surface to the radially inner surface. In aplane containing the longitudinal axis and the radial direction, thevalve seating surface may include a radially outer convex arcuatesegment defining an outer radius of curvature forming a first wear crownfor contacting the valve at an early wear state, a radially inner convexarcuate segment defining an inner radius of curvature forming a secondwear crown for contacting the valve at a later wear state, and a linearsegment extending between the radially outer convex arcuate segment andthe radially inner convex arcuate segment.

A valve seat insert according to an embodiment of the present disclosurefor a valve in an internal combustion engine may comprise an annularbody defining a valve seat cylindrical axis, and a radial direction thatis perpendicular to the valve seat cylindrical axis, a first axial endsurface, and a second axial end surface. The annular body may furtherhave a radially inner surface defining a throat, a radially outerperipheral surface defining a cooling gallery, and a valve seatingsurface extending between the radially inner surface and the secondaxial end surface. A top convex arcuate blend may extend from the firstaxial end surface to the radially inner surface. In a plane containingthe valve seat cylindrical axis and the radial direction, a radiallyouter convex arcuate segment may form a first wear crown, a radiallyinner convex arcuate segment may form a second wear crown, and a linearsegment may extend between the radially outer convex arcuate segment andthe radially inner convex arcuate segment.

A valve seat insert according to another embodiment of the presentdisclosure for a valve in an internal combustion engine may comprise anannular body defining a valve seat cylindrical axis, and a radialdirection that is perpendicular to the valve seat cylindrical axis, afirst axial end surface, and a second axial end surface. The annularbody may further have a radially inner surface defining a throat, aradially outer peripheral surface defining a cooling gallery, and avalve seating surface extending between the radially inner surface andthe second axial end surface. A top convex arcuate blend surface mayextend from the first axial end surface to the radially inner surface.In a plane containing the valve seat cylindrical axis and the radialdirection, a radially outer convex arcuate segment may forming a firstwear crown, a radially inner convex arcuate segment may form a secondwear crown, a linear segment may extend between the radially outerconvex arcuate segment and the radially inner convex arcuate segmentdefining a break-in contact width that is greater than 4.5 millimeters,and the top convex arcuate blend surface may define a top radius ofcurvature that is greater than 0.3 millimeters.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectioned side diagrammatic view of an internal combustionengine, according to a first embodiment of the present disclosure (e.g.a C280 diesel marine engine manufactured by the Applicant of the presentdisclosure).

FIG. 2 is a sectioned side diagrammatic view of an internal combustionengine, according to a second embodiment of the present disclosure (e.g.a G3600 gas marine engine manufactured by the Applicant of the presentdisclosure).

FIG. 3 is a sectioned side diagrammatic view of portions of a gasexchange (intake and/or exhaust) valve and valve seat insert, accordingto one embodiment of the present disclosure that may be used in theinternal combustion engine of FIG. 1 or FIG. 2.

FIG. 4 is an enlarged detail view taken from rectangle 4 of FIG. 3.

FIG. 5 is an enlarged detail view taken from rectangle 5 of FIG. 4.

FIG. 6 is a sectioned side diagrammatic view of portions of a gasexchange (intake and/or exhaust) valve and valve seat insert, accordingto another embodiment of the present disclosure where the valve seatinsert includes a conical surface that may provide a venturi effect foran intake valve or a diffuser effect for an exhaust valve that may beused in the internal combustion engine of FIG. 1 or FIG. 2.

FIG. 7 is a sectioned side diagrammatic view of portions of a gasexchange (e.g. exhaust) valve and valve seat insert, according to yetanother embodiment of the present disclosure that may be used in theinternal combustion engine of FIG. 1 or FIG. 2.

FIG. 8 is an enlarged detail view taken from rectangle 8 of FIG. 7.

FIG. 9 is an enlarged detail view taken from rectangle 9 of FIG. 8.

FIG. 10 is a sectioned side diagrammatic view of portions of a gasexchange (exhaust) valve and valve seat insert, according to anotherembodiment of the present disclosure similar to that of FIG. 7 where thevalve seat insert includes a conical surface that may provide a diffusereffect for an exhaust valve that may be used in the internal combustionengine of FIG. 1 or FIG. 2.

FIG. 11 is a sectioned side diagrammatic view of portions of a gasexchange (exhaust) valve and valve seat insert, according to anotherembodiment of the present disclosure similar to that of FIG. 10 wherethe valve seat insert includes modified geometry for the cooling gallerythat may be used in the internal combustion engine of FIG. 1 or FIG. 2.

FIG. 12 is a sectioned side diagrammatic view of portions of a gasexchange (exhaust) valve and valve seat insert, according to anotherembodiment of the present disclosure similar to that of FIG. 11 wherethe valve seat insert lacks the slanted surface that may be used in theinternal combustion engine of FIG. 1 or FIG. 2.

FIG. 13 is a comparative table of a valve seat insert in an engine headin proximity to an intake valve, according to various embodiments andprinciples of the present disclosure such as those shown FIGS. 3 thru 6,in comparison with a previous design to show reduced contact pressures.

FIG. 14 is a graph of flow coefficient in comparison to valvelift/diameter for intake port designs according to the presentdisclosure such as those shown in FIGS. 3 thru 6, and a previous design.

FIG. 15 is a comparative table of a valve seat insert in an engine headin proximity to an exhaust valve, according to various embodiments andprinciples of the present disclosure such as those shown FIGS. 7 thru12, in comparison with a previous design to show reduced contactpressures.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the disclosure,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts. In some cases, a referencenumber will be indicated in this specification and the drawings willshow the reference number followed by a letter for example, 100 a, 100 bor a prime indicator such as 100′, 100″ etc. It is to be understood thatthe use of letters or primes immediately after a reference numberindicates that these features are similarly shaped and have similarfunction such as is often the case when geometry is mirrored about aplane of symmetry. For ease of explanation in this specification,letters or primes will often not be included herein but may be shown inthe drawings to indicate duplications of features discussed within thiswritten specification.

Referring to FIG. 1, there is shown an internal combustion engine 100according to one embodiment and including an engine housing 102 having acylinder block 104 with a cylinder 106 (may also be referred to a“bore”) formed therein. Internal combustion engine 100 could be any of avariety of engines including a compression ignition diesel engine, aspark-ignited gasoline engine, a gaseous fuel engine structured tooperate on a fuel that is gaseous at standard temperature and pressure,a dual fuel engine, or still another. In a compression ignition dieselengine application, such as a direct-injected diesel engine, suitablefuels could include diesel distillate fuel, biodiesel, blends of these,or still others. For the embodiments discussed herein in particularity,the engine may be a high power density C280 engine or other marineengines manufactured by the Applicant of the present disclosure. Otherapplications are to be considered within the scope of the presentdisclosure.

Similarly, in FIG. 2, there is shown an internal combustion engine 200according to another embodiment that has an engine housing 202 having acylinder block 204 with a cylinder 206 (may also be referred to a“bore”) formed therein. Internal combustion engine 200 could be any of avariety of engines including a compression ignition diesel engine, aspark-ignited gasoline engine, a gaseous fuel engine structured tooperate on a fuel that is gaseous at standard temperature and pressure,a dual fuel engine, or still another. In a spark-ignited gasoline engineapplication, such as a direct-injected gas engine, suitable fuels couldinclude gasoline, etc. For the embodiments discussed herein inparticularity, the engine may be a high power density G3600 gas marineengine or other marine engines manufactured by the Applicant of thepresent disclosure. Other applications are to be considered within thescope of the present disclosure.

Looking at FIGS. 1 and 2 together, an engine head 108, 208 may becoupled to the cylinder block 104, 204 and has a first gas exchangeconduit 110, 210 and a second gas exchange conduit 112, 212 formedtherein. Gas exchange conduits 110, 210 and 112, 212 could each oreither be an intake conduit structured to fluidly connect with an intakemanifold or an exhaust conduit structured to connect with an exhaustmanifold. In a practical implementation strategy, gas exchange conduit110, 210 is an intake conduit and gas exchange conduit 112, 212 is anexhaust conduit.

A piston 114, 214 is movable within cylinder 106, 206 between a bottomdead center position and a top dead center position and is coupled to acrankshaft (not shown) by way of a connecting rod 116, 216 in agenerally conventional manner. Engine 100, 200 could include any numberof cylinders arranged in any suitable configuration such as a Vconfiguration, an in line configuration, or still another. Engine head108, 208 could include a monolithic engine head associated with all of aplurality of the cylinders in engine 100, 200, or could be one of aplurality of separate engine head sections each associated with lessthan all of the cylinders in engine 100, 200.

Engine 100, 200 further includes a first gas exchange valve 118, 218,which may include an intake valve, and a second gas exchange valve 120,220, which may include an exhaust valve. Gas exchange valves 118, 218,120, 220 including aspects of their structure and operation, isdiscussed herein in the singular, however, it will be understood thatthe description of gas exchange valve 118, 218, 120, 220 can apply byway of analogy to any other gas exchange valves within engines 100, 200,except where otherwise indicated. Gas exchange valves 118, 218, 120, 220are shown more or less vertically oriented with respect to a directionof reciprocation of piston 114, 214, however, it should also beappreciated that other configurations such as gas exchange valves atdiagonal orientations are contemplated herein. Gas exchange valves 118,218, 120, 220 also include a shaft or stem 122, 222 connected to a valvehead 124, 224.

As best seen in FIG. 2, a valve bridge 226 or the like may be coupled togas exchange valve 218, 220 such that gas exchange valve 218, 220 canmove together with another gas exchange valve (not shown) between openand closed positions, such as in response to rotation of a camshaft andmovement of a rocker arm, a valve lifter assembly, and/or otherequipment. A return spring 228 may be coupled with gas exchange valve218, 220 in a generally conventional manner to bias the valve toward aclosed position.

As seen in FIGS. 1 and 2, engine 100, 200 further includes an enginehead assembly 130, 230 formed by engine head 108, 208 and a plurality ofvalve seat inserts 300 and 400 associated with gas exchange valves 118,218, 120, 220. Gas exchange valves 118, 218, 120, 220 are movablebetween a closed valve position and an open valve position. At theclosed valve position, gas exchange valves 118, 218, 120, 220 contactvalve seat insert 300 or 400. At the closed position cylinder 106,206 isblocked from fluid communication with the corresponding gas exchangeconduit 110, 112, 210, 212. At the open valve position fluidcommunication exists. A combustion face of the valves is oriented towardcylinder.

As will also be further apparent from the following description, valveseat inserts 300, 400, are structured, together with the correspondinggas exchange valves, to slow and alter the nature of valve recessionover the course of a service life or service interval of engine 100, 200and to provide intake gas flow properties at least as efficacious as,and potentially improved over, known designs.

Turning now to FIG. 3, it may be understood that an engine head assembly230 for an internal combustion engine 200 such as those described abovemay comprise an engine head 208 having a fluid conduit formed (e.g. seeitem 210) formed therein, a valve 218, and a valve seat insert 300positioned at least partially within the engine head 208.

The valve seat insert 300 may include an at least partially annular body302 (e.g. may be a body of revolution such that the geometry does notalter along a circumferential direction, this may not be the case inother embodiments), defining a longitudinal axis 304, and a radialdirection 306 that is perpendicular the longitudinal axis 304, a firstaxial end surface 308 that is disposed proximate to the engine head 208,and a second axial end surface 310 facing toward the cylinder 206 (seeFIG. 2). A radially inner surface 312 that may form a throat 314 may beprovided, as well as a radially outer peripheral surface 316, and avalve seating surface 318 that is disposed axially and radially betweenthe radially inner surface 312, and the second axial end surface 310.Also, a top convex arcuate blend 320 may extend from the first axial endsurface 308 to the radially inner surface 312.

As used herein, “blend” includes any transitional geometry includingradii, polynomials, splines, ellipses, etc. Also, “arcuate” includes anyfeature that is not straight, flat, or planar.

In FIGS. 3 and 4, a cross-sectional plane is depicted that contains thelongitudinal axis 304, and the radial direction 306. The valve seatingsurface 318 may include a radially outer convex arcuate segment 322defining an outer radius of curvature forming a first wear crown 324 forcontacting the valve at an early wear state, a radially inner convexarcuate segment 326 defining an inner radius of curvature forming asecond wear crown 328 for contacting the valve at a later wear state,and a linear segment 330 extending between the radially outer convexarcuate segment 322 and the radially inner convex arcuate segment 326.

As best seen in FIG. 4, the linear segment 330 of the valve seatingsurface 318 defines a break-in contact width 332 that ranges from 4.0millimeters to 5.0 millimeters, and more particularly 4.2 millimeters to4.6 millimeters in some embodiments. Likewise, the outer radius ofcurvature may range from 1.5 millimeters to 6.0 millimeters, and theinner radius of curvature may range from 0.2 millimeters to 0.6millimeter. Various other values for these variables are possible.

For example, the break-in contact width for embodiments referred to as“Option 1”, “Option 2”, “Option 3”, and “Option 4” for an intake valvemay be approximately 4.41 millimeters. The outer radius of curvature maybe 5.4 millimeters (Option 1), 3.2 millimeters (Option 2), and 2.0millimeters (Options 3 and 4). The inner radius of curvature may be 0.4millimeters (Options 1, 2, 3 and 4).

In FIG. 3, it may be understood that the top convex arcuate blend 320may form a top flow crown 334 having a top flow crown radius ofcurvature that ranges from 0.3 millimeters to 2.0 millimeters. Forexample, the top flow crown radius of curvature may be 1.5 millimeters(Options 1, 2, and 3), and 0.5 millimeters (Option 4, see FIG. 6).

Looking at FIG. 6, a conical surface 336 may extend from the top convexarcuate blend 320 a to the throat 314 a. The conical surface 336 may beconfigured to form a venturi to accelerate an incoming flow of gases tothe cylinder in some embodiments. The conical surface 336 may form anacute angle 337 with the longitudinal axis 304 ranging from 0 degrees to10.0 degrees in some embodiments (e.g. about 6.0 degrees). Also, theradially inner surface 312 may include a cylindrical surface 338extending axially from the throat 314 a to the radially inner convexarcuate segment 326.

Looking at FIG. 3, the top flow crown 334 is radially offset a radialdistance 340 from the engine head 208, and the top convex arcuate blend320 defines a top flow crown radius of curvature that is equal to orless than the radial distance 340 (may approach zero as shown in FIG.6). Furthermore, the radially inner surface 312 may include acylindrical surface 338 a extending axially from the top convex arcuateblend 320 to the radially inner convex arcuate segment 326.

Referring now to FIGS. 2 and 3, the cylinder 206 is in fluidcommunication with the fluid conduit (e.g. 210, 212), and a piston 214may be disposed in the cylinder 206 that is configured to translateupwardly and downwardly in the cylinder 206. The valve 210 may bedisposed between the piston 214 and the valve seat insert 300. The valve210 may include an upwardly facing shut off surface 232 that isconfigured to engage and disengage the valve seat insert 300. Theupwardly facing shut off surface 232 may be conical as shown, planar,arcuate or any combination thereof.

The valve seat insert 300 that may be supplied as a replacement partaccording to an embodiment of the present disclosure will now bediscussed with reference to FIGS. 3 and 4.

The valve seat insert 300 may have an annular body 302 defining a valveseat cylindrical axis 304 a, and a radial direction 306 that isperpendicular to the valve seat cylindrical axis 304 a, a first axialend surface 308, and a second axial end surface 310. The annular body302 further include a radially inner surface 312 defining a throat 314,a radially outer peripheral surface 316, and a valve seating surface 318extending axially and radially between the radially inner surface 312,and the second axial end surface 310. A top convex arcuate blend 320 mayextend from the first axial end surface 308 to the radially innersurface 312.

In a plane (such as shown in FIGS. 3 and 4) containing the valve seatcylindrical axis 304 a, and the radial direction 306, a radially outerarcuate segment 322 a may form a first wear crown 324, a radially innerarcuate segment 326 a may form a second wear crown 328, and a linearsegment 330 may extend between the radially outer arcuate segment 322 a,and the radially inner arcuate segment 326 a. A vertical segment 342 maybe interposed axially between the first axial end surface 308, and thesecond axial end surface 310.

As shown in FIG. 6, a sloping segment 344 may extend between the topconvex arcuate blend 320 a, and the throat 314 a. In such a case, thesloping segment 344 may extend radially outwardly from the throat 314 atoward the top convex arcuate blend 320 a at an acute angle 337 of 3.0°or greater, relative to the valve seat cylindrical axis 304 a, such thatthe radially inner surface 312 a forms a venturi to accelerate anincoming flow of gases in an intake valve type application.

As alluded to above herein with reference to FIGS. 3 and 4, the topconvex arcuate blend 320 may define a top blend radius of curvature thatranges from 0.4 millimeters to 2.0 millimeters, the radially outerarcuate segment 322 a may define an outer radius of curvature thatranges from 1.5 millimeters to 6.0 millimeters, the radially innerarcuate segment 326 a may define an inner radius of curvature thatranges from 0.2 millimeters to 0.6 millimeters, and the linear segment330 of the valve seating surface 318 may define a break-in contact width332 that ranges from 4.0 millimeters to 5.0 millimeters.

Next, a valve seat insert 300 that may also be used as a replacementpart according to another embodiment of the present disclosure will nowbe discussed with reference to FIGS. 3 and 4.

In a plane containing the valve seat cylindrical axis 304 a, and theradial direction 306 such as shown in FIGS. 3 and 4, the valve seatingsurface 318 may have a radially outer convex arcuate segment 322 forminga first wear crown 324, a radially inner convex arcuate segment 326forming a second wear crown 328, a linear segment 330 extending axiallyand radially between the radially outer convex arcuate segment 322, andthe radially inner convex arcuate segment 326 may define a break-incontact width 322 that is greater than 3.9 millimeters. Also, the topconvex arcuate blend surface 321 may define a top radius of curvaturethat is greater than 0.3 millimeters.

Similarly, the radially outer convex arcuate segment 322 may define aradially outer convex radius of curvature that is greater than 1.9millimeters, and the radially inner convex arcuate segment 326 maydefine a radially inner convex radius of curvature that is greater than0.2 millimeters.

In FIG. 3, a vertical segment 342 may extend from the top convex arcuateblend surface 321 to the radially inner convex arcuate segment 326,defining a vertical length 346 that ranges from 13.5 millimeters to 14.5millimeters. Also, the throat 314 defines a throat diameter 348 thatranges from 78.0 millimeters to 79.6 millimeters in some embodiments.

In FIG. 6, a vertical segment 342 a extends from the throat 314 a to theradially inner convex arcuate segment 326, defining a vertical length346 a that ranges from 2.0 millimeters to 3.0 millimeters, and a slopingsegment 344 that extends from the throat 314 a to the top convex arcuateblend surface 321.

As further discussed herein with reference to FIGS. 3 thru 6, the valveseat insert 300 may have a proportionally larger valve seating surfacearea than certain prior designs, and somewhat less available flow areafor gas exchange, with the improved venturi-accelerated flowcompensating for, or more than compensating for, what might otherwise beexpected to be reduced performance.

The radially outer peripheral surface 316 has a cylindrical shape andmay be located at a uniform distance from valve seat cylindrical axis304 a. In an implementation, valve seat insert 300 is “dry,” meaningthat no additional cooling by way of engine coolant or the like isemployed. The radially outer peripheral surface 316 may be uninterruptedin abutment against engine head 208, such that when valve seat insert300 is positioned within engine head 208 for service, such as by way ofan interference fit, there is no backside cooling void, or other cavityformed that provides liquid cooling to valve seat insert 300. A chamfer350 may extend between the radially outer peripheral surface 316, andthe first axial end surface 308. Similar statements may be made withrespect to an exhaust valve application.

Initial contact when valve seat insert 300 and gas exchange valve 218are first placed in service may occur at a contact band at the firstwear crown 324. As the respective components deform and wear they maytransition from an early wear state where the components have a linecontact, or nearly line contact, band formed at the first wear crown324, to full face contact, and a still later wear state where full facecontact is maintained but transitions also to contact with the secondwear crown 328. It should be appreciated that the term “early wearstate” and the term “later wear state” are used herein in relation toone another, not necessarily meaning that “early” contemplates new northat “later” contemplates old, although such terms could apply in anactual case. Certain basic principles illustrated relative to profilingof valve seating surface 318 have application to a number of differentembodiments, some having additional or alternative structural details,as further discussed herein.

In the illustrations of FIGS. 4 and 5, it can also be seen that the shutoff surface 232 is oriented at a valve angle 234 relative to ahorizontal plane that is oriented normal to valve seat cylindrical axis304 a. Linear segment 330 is oriented at a seat angle 352 relative tothe horizontal plane that is larger than valve angle 234. Thus, aninterference angle 236 is formed by the shut off surface 232 and thelinear segment 330, and a clearance 238 (ranging from 0.018 mm to 0.025mm) is formed between the shut off surface 232 and the linear segment330. The valve angle 234 may differ from the seat angle 352 by about0.2° to about 0.3° (e.g. about 0.25°). Seat angle 352 may be from about15° to about 25°, and seat angle 352 may be about 20° in one practicalimplementation. As used herein, the term “about” should be understood inthe context of conventional rounding to a consistent number ofsignificant digits. Accordingly, “about 20” means from 19.5 to 20.4,“about 19.5” means from 19.45 to 19.54, and so on.

A second clearance 240 may be formed between the shut off surface 232and the radially outer convex arcuate segment 322 and extends radiallyoutward and axially outward from a contact band formed at the early wearstate approximately as depicted, at the first wear crown 324. It will berecalled that the initial contact band may have an annular form and maybe substantially a line contact pattern but expected to commencechanging toward a face contact pattern as early break-in occurs. A sizeof the second clearance 240 may include a facing length 242 that isabout 0.80 millimeter to about 1.6 millimeters (e.g. about 1.528millimeters for Option 1, about 1.13 millimeters for Option 2, about0.913 millimeter for Option 3, about 0.926 millimeter for Option 4),between the shut off surface 232 and the radially outer convex arcuatesegment 322. Facing length 242 can be understood as the distance fromthe contact band to an outer edge of the upwardly facing shut offsurface 232 of the valve head 224. A maximum vertical clearancedimension 244 is also shown to range from 0.190 millimeter to 0.210millimeter (about 0.206 millimeter for Option 1, 0.189 millimeter forOptions 2, 3, and 4).

Also shown in FIG. 4 is a full seating width dimension 354 ortheoretical full seating width of valve seat insert 300 that mayeventually become available as wear between the components progresses,in comparison to a break-in face contact width obtained when full facecontact initially occurs. The full seating width dimension 354 may rangefrom 5.4 millimeters to 6.9 millimeters (about 6.68 millimeters forOption 1, about 5.91 millimeters for Option 2, about 5.48 millimetersfor Option 3, about 5.49 millimeters for Option 4).

Any of the aforementioned features may be differently configured or havedifferent dimensions that what has been specifically stated herein.

Turning now to FIG. 7, it may understood that an engine head assembly130 for an internal combustion engine 100 may comprise an engine head108 having a fluid conduit formed therein (e.g. see 112), a valve 120,and a valve seat insert 400 positioned at least partially within theengine head 108.

The valve seat insert 400 may include an at least partially annular body402 defining a longitudinal axis 404, and a radial direction 406 that isperpendicular the longitudinal axis 404. A first axial end surface 408may be disposed proximate to the engine head 108, and a second axial endsurface 410 may face toward the cylinder 106 (see FIG. 1).

The valve seat insert 400 may also have a radially inner surface 412forming a throat 414, a radially outer peripheral surface 416 defining acooling gallery 480 (e.g. to cool the insert when exposed to exhaustgases in an exhaust valve application), and a valve seating surface 418disposed axially and radially between the radially inner surface 412,and the second axial end surface 410. Also, a top convex arcuate blend420 may extend from the first axial end surface 408 to the radiallyinner surface 412, defining a top flow crown 434.

FIGS. 7 and 8 illustrate a cross-sectional plane containing thelongitudinal axis 404, and the radial direction 406 In that plane, thevalve seating surface 418 may include a radially outer convex arcuatesegment 422 defining an outer radius of curvature forming a first wearcrown 424 for contacting the valve 120 at an early wear state, aradially inner convex arcuate segment 426 defining an inner radius ofcurvature forming a second wear crown 428 for contacting the valve 120at a later wear state, and a linear segment 430 extending between theradially outer convex arcuate segment 422, and the radially inner convexarcuate segment 426.

As best seen in FIG. 7, the valve seat insert 400 may further comprise alower planar shelf surface 482 that is disposed radially and axiallyadjacent the valve seating surface 418, and a radially outer conicalsurface 484 disposed radially and axially between the lower planar shelfsurface 482, and the second axial end surface 410.

The radially outer peripheral surface 416 may include a radially innercylindrical surface 486 extending from the first axial end surface 408,a radially outer cylindrical surface 488 extending from the second axialend surface 410, and an upper planar shelf surface 490 that isinterposed radially and axially between the radially inner cylindricalsurface 486, and the radially outer cylindrical surface 488. The coolinggallery 480 may extend from the upper planar shelf surface 490, and theradially inner cylindrical surface 486.

Looking now at FIGS. 10 and 11, a radially inner conical surface 436,436 a may extend from the top convex arcuate blend 420 to the throat414. This radially inner conical surface 436, 436 a may be configured toform a diffuser to decelerate an outgoing flow of gases. In such a case,the radially inner conical surface 436, 436 a may form an acute angle437, 437 a with the longitudinal axis 404 ranging from 5.0 degrees to15.0 degrees (e.g. about 7.125 degrees for Option 4 for the exhaustapplication in FIG. 11, about 12.0 degrees for Option 3 for the exhaustapplication in FIG. 10).

Referring back to FIG. 8, the linear segment 430 of the valve seatingsurface 418 may define a break-in contact width 432 that ranges from 4.5millimeters to 5.0 millimeters (e.g. 4.9 millimeters for Option 1, 4.88millimeters for Option 2, 5.12 millimeters for Option 3, 4.826millimeters for Option 4, 4.655 millimeters for Options 6 and 7).

Likewise, the top convex arcuate blend 420 (see FIG. 7) forms a top flowcrown 434 having a the top flow crown radius of curvature that rangesfrom 0.3 millimeter to 1.5 millimeters (e.g. 1.0 millimeter for Options1 thru 3, 0.5 millimeters for Options 4 thru 7), the outer radius ofcurvature of 422 (see FIG. 8) ranges from 1.5 millimeters to 6.0millimeters (e.g. 3.2 millimeters for Option 1, 5.4 millimeters forOptions 2, 4, 6, 7, 2.0 millimeters for Option 3), and the inner radiusof curvature of 426 (see FIG. 8) ranges from 0.2 millimeter to 1.0millimeter (e.g. 0.4 millimeter for Option 2, 0.6 millimeter for Option3, 0.5 millimeter for Options 4 and 7, 0.8 millimeter for Option 6).

As best seen in FIG. 12, the top flow crown 434 may be radially offset aradial distance 440 from the engine head 108, and the top convex arcuateblend 420 defines a top flow crown radius of curvature that is equal toor greater than the radial distance 440. This may not the case for allembodiments (e.g. see FIG. 10).

With continued reference to FIG. 12, the radially inner surface 412 mayinclude a radially inner cylindrical surface 470 that extends axiallyfrom the top convex arcuate blend 420 to the radially inner convexarcuate segment 426.

In FIGS. 10 and 12, the radially inner surface 412 a, 412 b may includea cylindrical surface 472, 472 a extending axially from the throat 414a, 414 b to the radially inner convex arcuate segment 426 a, 426 b.

The valve seat insert 400 that may be supplied as a replacement partaccording to an embodiment of the present disclosure will now bediscussed with reference to FIGS. 7 and 8.

The valve seat insert 400 may comprise an annular body 402 defining avalve seat cylindrical axis 404 a, and a radial direction 406 that isperpendicular to the valve seat cylindrical axis 404 a. A first axialend surface 408, and a second axial end surface 410 may be disposedalong the axis 404 a.

The annular body 402 may further have a radially inner surface 412defining a throat 414, a radially outer peripheral surface 416 defininga cooling gallery 480, and a valve seating surface 418 that extendsbetween the radially inner surface 412, and the second axial end surface410. A top convex arcuate blend 420 may extend from the first axial endsurface 408 to the radially inner surface 412.

In the plane of FIGS. 7 and 8, it may be understood that a radiallyouter convex arcuate segment 422 forming a first wear crown 424, aradially inner convex arcuate segment 426 forming a second wear crown428, and a linear segment 430 extending between the radially outerarcuate segment 422, and the radially inner convex arcuate segment 426may be provided. Also, a vertical segment 442 may be interposed axiallybetween the first axial end surface 408, and the second axial endsurface 410.

In addition as seen in FIGS. 10 and 11, the radially inner surface 412may include a sloping segment 444, 444 a that may extend between the topconvex arcuate blend 420 and the throat 414 a, 414 b. In such anembodiment, the sloping segment 444, 444 a may extend radially outwardlyfrom the throat 414 a, 414 b toward the top convex arcuate blend 420 atan acute angle 437, 437 a of 5.0° such that the radially inner surface412 a, 412 b forms a diffuser to decelerate an outgoing flow of gases.

As alluded to earlier herein with reference to FIG. 8, the top convexarcuate blend 420 may define a top blend radius of curvature that rangesfrom 0.3 millimeters to 1.5 millimeters, the radially outer convexarcuate segment 422 may define an outer radius of curvature that rangesfrom 1.5 millimeters to 6.0 millimeters, the radially inner convexarcuate segment 426 may define an inner radius of curvature that rangesfrom 0.2 millimeters to 1.0 millimeters, and the linear segment 430 ofthe valve seating surface 418 may define a break-in contact width 432that ranges from 4.5 millimeters to about 5.5 millimeters.

Next, a valve seat insert 400 that may also be used as a replacementpart according to yet another embodiment of the present disclosure willnow be discussed starting with FIGS. 7 and 8.

The valve seat insert 400 may include a top convex arcuate blend surface420 a may extend from the first axial end surface 408 to the radiallyinner surface 412. A radially outer convex arcuate segment 422 forming afirst wear crown 424, and a radially inner convex arcuate segment 426forming a second wear crown 428 may also be provided. A linear segment430 may extend between the radially outer convex arcuate segment 422,and the radially inner convex arcuate segment 426, defining a break-incontact width 432 that is greater than 4.5 millimeters. The top convexarcuate blend surface 420 a may define a top radius of curvature that isgreater than 0.3 millimeters in some embodiments.

In some embodiments, the radially outer convex arcuate segment 422 maydefine a radially outer convex radius of curvature that is greater than1.5 millimeters, and the radially inner convex arcuate segment 426 maydefine a radially inner convex radius of curvature that is greater than0.2 millimeters.

The valve seat insert 400 may further comprise a lower planar shelfsurface 482 that is disposed radially and axially adjacent the valveseating surface 418, and a radially outer conical surface 484 that isdisposed radially and axially between the lower planar shelf surface482, and the second axial end surface 410.

In FIG. 12, it can be seen that the radially outer peripheral surface416 a includes a radially inner cylindrical surface 486 a extending fromthe first axial end surface 408, a radially outer cylindrical surface488 a extending from the second axial end surface 410, and an upperplanar shelf surface 490 that is interposed radially and axially betweenthe radially inner cylindrical surface 486 a, and the radially outercylindrical surface 488 a. The cooling gallery 480 a may extend from theupper planar shelf surface 490, and the radially inner cylindricalsurface 486 a.

The first axial end surface 408 may be spaced away from the upper planarshelf surface 490 a first axial distance 491 that ranges from 18.5millimeters to 20.0 millimeters (e.g. 19.25 millimeters), while thesecond axial end surface 410 may be spaced away from the upper planarshelf surface a second axial distance 492 that ranges from 12.0millimeters to 14.0 millimeters (e.g. 13.0 millimeters)

In the plane of FIG. 12, it can be understood that the cooling gallery480 a may be defined by an upper slanted segment 493 that extendsradially inwardly and axially downwardly to a straight axially extendingsegment 494 that extends axially downwardly to a semicircular segment496 that extends radially outwardly to an axially upwardly extendingsegment 498 that connects to the upper planar shelf surface 490. Theradius of curvature of 496 may be about 2.5 millimeters, the coolinggallery 480 a may be spaced away from the first axial end surface 408about 9.0 millimeters, and the lower planar shelf surface 482 may bespaced away from the second axial end surface 410 about 13.0 millimetersin certain embodiments. Also, the throat diameter of the valve seatinsert 400 may be similar to or the same as that of the valve seatinsert 300 as discussed earlier herein.

As further discussed herein with reference to FIGS. 7 thru 12, the valveseat insert 400 may have a proportionally larger valve seating surfacearea than certain prior designs, and somewhat less available flow areafor gas exchange, with the improved venturi-accelerated flow provided byradially outer conical surface 484 compensating for, or more thancompensating for, what might otherwise be expected to be reducedperformance.

In an implementation, valve seat insert 400 is “wet”, meaning thatadditional cooling by way of engine coolant or the like is employed. Thevalve seat insert 400 is positioned within engine head 108 for service,such as by way of an interference fit, and there is a backside coolingvoid (or cooling gallery 480, 480 a), or other cavity formed thatprovides liquid cooling to valve seat insert 400. A chamfer 450 mayextend between the radially outer peripheral surface 416, and the firstaxial end surface 408. Similar statements may be made with respect to anintake valve application.

Initial contact when valve seat insert 400 and gas exchange valve 120are first placed in service may occur at a contact band at the firstwear crown 424. As the respective components deform and wear they maytransition from an early wear state where the components have a linecontact, or nearly line contact, band formed at the first wear crown424, to full face contact, and a still later wear state where full facecontact is maintained but transitions also to contact with the secondwear crown 428. It should be appreciated that the term “early wearstate” and the term “later wear state” are used herein in relation toone another, not necessarily meaning that “early” contemplates new northat “later” contemplates old, although such terms could apply in anactual case. Certain basic principles illustrated relative to profilingof valve seating surface 418 have application to a number of differentembodiments, some having additional or alternative structural details,as further discussed herein.

In the illustrations of FIGS. 8 and 9, it can also be seen that the shutoff surface 132 is oriented at a valve angle 134 relative to ahorizontal plane that is oriented normal to valve seat cylindrical axis404 a. Linear segment 430 is oriented at a seat angle 452 relative tothe horizontal plane that is larger than valve angle 134. Thus, aninterference angle 136 is formed by the shut off surface 132 and thelinear segment 430, and a clearance 138 (ranging from 0.04 mm to 0.045mm) is formed between the shut off surface 132 and the linear segment430. The valve angle 134 may differ from the seat angle 452 by about0.4° to about 0.6° (e.g. about 0.5°). Seat angle 452 may be from about25° to about 35°, and seat angle 452 may be about 30° in one practicalimplementation. As used herein, the term “about” should be understood inthe context of conventional rounding to a consistent number ofsignificant digits. Accordingly, “about 20” means from 19.5 to 20.4,“about 19.5” means from 19.45 to 19.54, and so on.

A second clearance 140 may be formed between the shut off surface 132and the radially outer convex arcuate segment 422 that extends radiallyoutward and axially outward from a contact band formed at the early wearstate approximately as depicted, at the first wear crown 424. It will berecalled that the initial contact band may have an annular form and maybe substantially a line contact pattern but expected to commencechanging toward a face contact pattern as early break-in occurs. A sizeof the second clearance 140 may include a facing length 142 that isabout 0.80 millimeter to about 2.0 millimeters (e.g. about 1.25millimeters for Option 1, about 1.86 millimeters for Options 2 and 7,about 0.931 millimeter for Option 3, about 0.861 millimeter for Options4, 6), between the shut off surface 132 and the radially outer convexarcuate segment 422. Facing length 142 can be understood as the distancefrom the contact band to an outer edge of the upwardly facing shut offsurface 132 of the valve head 124. A maximum vertical clearancedimension 144 is also shown to range from 0.180 millimeter to 0.250millimeter (about 0.229 millimeter for Option 1, 0.179 millimeter forOption 2, 0.198 millimeter for Option 3, 0.179 millimeter for Options 4,6 and 7).

Also shown in FIG. 8 is a full seating width dimension 454 ortheoretical full seating width of valve seat insert 400 that mayeventually become available as wear between the components progresses,in comparison to a break-in face contact width obtained when full facecontact initially occurs. The full seating width dimension 454 may rangefrom 6.5 millimeters to 8.5 millimeters (about 6.89 millimeters forOption 1, about 8.0 millimeters for Option 2, about 6.6 millimeters forOption 3, about 7.117 millimeters for Options 4 and 6, about 6.941millimeters for Option 7). A concave blend 456 may connect the lowerplanar shelf surface 482 and the radially outer conical surface 484 thatmay range from about 2.0 millimeters to about 3.0 millimeters ins someembodiments (see FIG. 7).

Any of the aforementioned features may be differently configured or havedifferent dimensions that what has been specifically stated herein. Anyof the valve seat inserts discussed herein may be cast, machined andformed of a steel such as a high-alloy hardened steel or tool steel.

INDUSTRIAL APPLICABILITY

In practice, a machine, an engine used by the machine, a valve seatinsert, a valve, and/or any combination of these various assemblies andcomponents may be manufactured, bought, or sold to retrofit a machine,or an engine already in the field in an aftermarket context, oralternatively, may be manufactured, bought, sold or otherwise obtainedin an OEM (original equipment manufacturer) context.

As alluded to previously herein, the aforementioned embodiments mayincrease the life of the valve seat insert and/or valve whilemaintaining or even improving engine performance(s) as will beelaborated further herein momentarily.

Referring now to FIG. 13, there is a comparative table showing how theembodiments (e.g. Options 1 thru 4) of the present disclosure for anintake valve have reduced the contact pressures (stresses) by as much as40% or more compared to previous designs (Baseline). This may be due toincreased contact area between the valve and the valve seat. So, oneskilled in the art would expect that various embodiments of the presentdisclosure will have an improved longevity, necessitating lessmaintenance over the life of the engine.

Similarly, FIG. 14 shows a graph for an intake valve showing the flowcoefficient is within 5% as compared to previous designs. This indicatesthat other engine performances involving fluid mechanics such ascombustion have unexpectedly not been adversely impacted. This may beattributed to the venturi effect created by the new designs.

Looking at FIG. 15, there is a comparative table showing how theembodiments (e.g. Options 1, 2 and 3) of the present disclosure for anexhaust valve have reduced the contact pressures (stresses) by as muchas 40% or more compared to previous designs (Baseline). This may be dueto increased contact area between the valve and the valve seat. So, oneskilled in the art would expect that various embodiments of the presentdisclosure will have an improved longevity, necessitating lessmaintenance over the life of the engine.

Valve seat inserts can play a key role in engine performance anddurability by way of wear performance for engine head life. Optimizingair flow at the same time as reducing wear has proven to be a greatchallenge. During operating an engine, intake valves reciprocate intoand out of contact with a valve seat insert. Gases including air or airmixed with other gases such as recirculated exhaust gas or gaseous fuel,is typically supplied at a pressure greater than atmospheric pressure tothe engine, such as from a turbocharger compressor. Downward travel of apiston in conjunction with the pressurization of the intake gases,causes the intake gases to rush into the cylinder as the piston movesfrom a top dead center position toward a bottom dead center position inan intake stroke so long as the intake valve is open.

According to the present disclosure, intake gases encountering top flowcrown will tend to flow relatively smoothly past top flow crown andenter the venturi when a funnel surface is provided. The smooth andaccelerating flow through the valve seat inserts of the presentdisclosure can compensate for, or more than compensate for, the reducedflow area as compared to the design of valve seat insert and otherdesigns with sacrificing valve seat or valve performance or engineservice life.

FIG. 14 shows that the intake port flow coefficient of variousembodiments of the present disclosure is about the same as that ofprevious designs. So, one skilled in the art would not expect adegradation of the engine performance in terms of fluid mechanics,thermodynamics, emissions, etc. while also reducing the interval neededfor maintaining the valve seat insert or the valve, etc. Thus, oneskilled in the art may surmise that the compromise (tradeoff) betweenlongevity and other engine performances has been broken using variousembodiments of the present disclosure.

The wear crowns discussed herein, in conjunction with the valve seatingcontact widths, seat angles, valve angles, and other geometric features,are designed in a manner that can be understood as cushioningvalve-valve seat impacts to reduce valve seat beat-in as well as slowingcertain wear modes. Providing a valve seat geometry in line with suchgoals can improve over valve seat designs such as that used in valveseat insert 300, 400 but has been discovered to place certainlimitations on the design of other valve seat insert characteristicssuch as gas flow properties.

Along such lines, the geometry of valve seat insert 300, 400 withrespect to intake valve seating properties, and the geometry of valveseat insert 300, 400 with respect to intake gas flow properties can beunderstood as a system of cross-coupled variables where modifying oneaspect of valve seat insert geometry can affect another aspect of valveseat insert geometry, often in unpredictable ways. For instance,providing second wear crown tends to require throat diameter to bereduced if valve seating diameter is to be maintained or increased. Inthe case of second wear crown too large a radius could impact flow area,acute angle, seat angle, or other parameters. Too small a radius couldfail to provide desired flow patterns and/or compromise desired valveseating performance.

Incorporating top flow crown and positioning top flow crown so as to beset off from the engine head can further reduce available flow area overwhat might be obtained with a valve seat insert having no top flow crownand no set off from the engine head. If the radius forming a top flowcrown is too small, for instance, the beneficial effects on incomingflow of intake gases might not be realized.

When a venturi is provided, then if the radius forming a top flow crownis too large, then the acute angle might be too narrow to achieve adesired acceleration of flow. Additional factors such as determining asuitable acute angle range, a seat angle range, whether a second flowcrown is used, and still others can have similar effect. Where more thanone design parameter is varied from design to design, the effects onperformance can be still more complex and unpredictable. For thesegeneral reasons, it will be appreciated that the optimized designs andparametric guidelines of the present disclosure offer a practicalbalancing of factors bearing on valve seating and intake gas flowperformance. In some cases, the compromise may actually be broken.

In summary, various embodiments of the present disclosure have novelseat geometry that lowers contact stress by as much as 45%, cuts thewear rate in half, lowers valve temperatures, and doubles the expectedlife of the valve seat insert. Cost is not increased since the amount oftime necessary to manufacture the seats has not significantly changed.

The present description is for illustrative purposes only, and shouldnot be construed to narrow the breadth of the present disclosure in anyway. Thus, those skilled in the art will appreciate that variousmodifications might be made to the presently disclosed embodimentswithout departing from the full and fair scope and spirit of the presentdisclosure. Other aspects, features and advantages will be apparent uponan examination of the attached drawings and appended claims. As usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Where onlyone item is intended, the term “one” or similar language is used. Also,as used herein, the terms “has,” “have,” “having,” “include”,“includes”, “including”, or the like are intended to be open-endedterms. Further, the phrase “based on” is intended to mean “based, atleast in part, on” unless explicitly stated otherwise.

All references to the disclosure or examples thereof are intended toreference the particular example being discussed at that point and arenot intended to imply any limitation as to the scope of the disclosuremore generally. All language of distinction and disparagement withrespect to certain features is intended to indicate a lack of preferencefor those features, but not to exclude such from the scope of thedisclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

Certain steps of any method may be omitted, performed in an order thatis different than what has been specifically mentioned or in some casesperformed simultaneously or in sub-steps. Furthermore, variations ormodifications to certain aspects or features of various embodiments maybe made to create further embodiments and features and aspects ofvarious embodiments may be added to or substituted for other features oraspects of other embodiments in order to provide still furtherembodiments.

Accordingly, this disclosure includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

What is claimed is:
 1. An engine head assembly for an internalcombustion engine comprising: an engine head having a fluid conduitformed therein; a valve; a valve seat insert positioned at leastpartially within the engine head, and the valve seat insert including anat least partially annular body, defining a longitudinal axis, and aradial direction that is perpendicular to the longitudinal axis, a firstaxial end surface disposed proximate to the engine head, and a secondaxial end surface; a radially inner surface forming a throat, a radiallyouter peripheral surface defining a cooling gallery, and a valve seatingsurface disposed axially and radially between the radially inner surfaceand the second axial end surface; and a top convex arcuate blendextending from the first axial end surface to the radially innersurface; wherein in a plane containing the longitudinal axis and theradial direction, the valve seating surface includes a radially outerconvex arcuate segment defining an outer radius of curvature forming afirst wear crown for contacting the valve at an early wear state, aradially inner convex arcuate segment defining an inner radius ofcurvature forming a second wear crown for contacting the valve at alater wear state, and a linear segment extending between the radiallyouter convex arcuate segment and the radially inner convex arcuatesegment.
 2. The engine head assembly of claim 1 wherein the valve seatinsert further comprises a lower planar shelf surface disposed radiallyand axially adjacent the valve seating surface, and a radially outerconical surface disposed radially and axially between the lower planarshelf surface and the second axial end surface.
 3. The engine headassembly of claim of claim 1 wherein the radially outer peripheralsurface includes a radially inner cylindrical surface extending from thefirst axial end surface, a radially outer cylindrical surface extendingfrom the second axial end surface, and an upper planar shelf surfaceinterposed radially and axially between the radially inner cylindricalsurface and the radially outer cylindrical surface, and the coolinggallery extends from the upper planar shelf surface and the radiallyinner cylindrical surface.
 4. The engine head assembly of claim of claim1 further comprising a radially inner conical surface extending from thetop convex arcuate blend to the throat, the radially inner conicalsurface being configured to form a diffuser to decelerate an outgoingflow of gases.
 5. The engine head assembly of claim 4 wherein theradially inner conical surface forms an acute angle with thelongitudinal axis ranging from 5.0 degrees to 15.0 degrees.
 6. Theengine head assembly of claim 5 wherein the linear segment of the valveseating surface defines a break-in contact width that ranges from 4.5millimeters to 5.0 millimeters.
 7. The engine head assembly of claim 6wherein the top convex arcuate blend forms a top flow crown having a thetop flow crown radius of curvature that ranges from 0.3 millimeter to1.5 millimeters, the outer radius of curvature ranges from 1.5millimeters to 6.0 millimeters, and the inner radius of curvature rangesfrom 0.2 millimeter to 1.0 millimeter.
 8. The engine head assembly ofclaim 7 wherein the top flow crown is radially offset a radial distancefrom the engine head, and the top convex arcuate blend defines a topflow crown radius of curvature that is equal to or greater than theradial distance.
 9. The engine head assembly of claim 1 wherein theradially inner surface includes a radially inner cylindrical surfaceextending axially from the top convex arcuate blend to the radiallyinner convex arcuate segment.
 10. The engine head assembly of claim 4wherein the radially inner surface includes a cylindrical surfaceextending axially from the throat to the radially inner convex arcuatesegment.
 11. A valve seat insert for a valve in an internal combustionengine comprising: an annular body defining a valve seat cylindricalaxis, and a radial direction that is perpendicular to the valve seatcylindrical axis, a first axial end surface, and a second axial endsurface; the annular body further having a radially inner surfacedefining a throat, a radially outer peripheral surface defining acooling gallery, and a valve seating surface extending between theradially inner surface and the second axial end surface; and a topconvex arcuate blend extending from the first axial end surface to theradially inner surface; wherein the valve seating surface includes in aplane containing the valve seat cylindrical axis and the radialdirection, a radially outer convex arcuate segment forming a first wearcrown, a radially inner convex arcuate segment forming a second wearcrown, and a linear segment extending between the radially outer convexarcuate segment and the radially inner convex arcuate segment.
 12. Thevalve seat insert of claim 11 wherein the radially inner surfaceincludes in a plane containing the valve seat cylindrical axis and theradial direction, a vertical segment interposed axially between thefirst axial end surface and the second axial end surface.
 13. The valveseat insert of claim 12 wherein the radially inner surface includes in aplane containing the valve seat cylindrical axis and the radialdirection, a sloping segment extending between the top convex arcuateblend and the throat.
 14. The valve seat insert of claim 11 wherein thesloping segment extends radially outwardly from the throat toward thetop convex arcuate blend at an acute angle of 5.0° or greater relativeto the valve seat cylindrical axis such that the radially inner surfaceforms a diffuser to decelerate an outgoing flow of gases.
 15. The valveseat insert of claim 11 wherein the top convex arcuate blend defines atop blend radius of curvature that ranges from 0.3 millimeters to 1.5millimeters, the radially outer convex arcuate segment defines an outerradius of curvature that ranges from 1.5 millimeters to 6.0 millimeters,the radially inner convex arcuate segment defines an inner radius ofcurvature that ranges from 0.2 millimeters to 1.0 millimeters, and thelinear segment of the valve seating surface defines a break-in contactwidth that ranges from 4.5 millimeters to about 5.5 millimeters.
 16. Avalve seat insert for a valve in an internal combustion enginecomprising: an annular body defining a valve seat cylindrical axis, anda radial direction that is perpendicular to the valve seat cylindricalaxis, a first axial end surface, and a second axial end surface; theannular body further having radially inner surface defining a throat, aradially outer peripheral surface defining a cooling gallery, and avalve seating surface extending between the radially inner surface andthe second axial end surface; and a top convex arcuate blend surfaceextending from the first axial end surface to the radially innersurface; wherein the valve seating surface includes in a planecontaining the valve seat cylindrical axis and the radial direction, aradially outer convex arcuate segment forming a first wear crown, aradially inner convex arcuate segment forming a second wear crown, alinear segment extending between the radially outer convex arcuatesegment and the radially inner convex arcuate segment defining abreak-in contact width that is greater than 4.5 millimeters, and the topconvex arcuate blend surface defines a top radius of curvature that isgreater than 0.3 millimeters.
 17. The valve seat insert of claim 16wherein the radially outer convex arcuate segment defines a radiallyouter convex radius of curvature that is greater than 1.5 millimeters,and the radially inner convex arcuate segment defines a radially innerconvex radius of curvature that is greater than 0.2 millimeters.
 18. Thevalve seat insert of claim 16 wherein the valve seat insert furthercomprises a lower planar shelf surface disposed radially and axiallyadjacent the valve seating surface, and a radially outer conical surfacedisposed radially and axially between the lower planar shelf surface andthe second axial end surface.
 19. The valve seat insert of claim 16wherein the radially outer peripheral surface includes a radially innercylindrical surface extending from the first axial end surface, aradially outer cylindrical surface extending from the second axial endsurface, and an upper planar shelf surface interposed radially andaxially between the radially inner cylindrical surface and the radiallyouter cylindrical surface, and the cooling gallery extends from theupper planar shelf surface and the radially inner cylindrical surface.20. The valve seat insert of claim 16 wherein the first axial endsurface is spaced away from the upper planar shelf surface a first axialdistance that ranges from 18.5 millimeters to 20.0 millimeters, thesecond axial end surface is spaced away from the upper planar shelfsurface a second axial distance that ranges from 12.0 millimeters to14.0 millimeters, and the cooling gallery is defined in the planecontaining the valve seat cylindrical axis and the radial direction, andincludes an upper slanted segment that extends radially inwardly andaxially downwardly to a straight axially extending segment, that extendsaxially downwardly to a semicircular segment that extends radiallyoutwardly to an axially upwardly extending segment that connects to theupper planar shelf surface.